Hello,
Thank you for your query at DoctorSpring.com
I understand your concern.
You have consistent post-nasal discharge and that itself is a cause of halitosis or bad breath.
Sometimes chronic sinus infections, or recurrent allergies present with a persistent post-nasal discharge.
I will first advise you to get a CT SCAN of the para nasal sinuses done, to see if sinus is the source. Based on that, I can advise you further.
Hope this was helpful
Regards.